Medical care is generally available in larger cities and in acceptable to good quality. In rural areas, finding good doctors or hospitals can be difficult. Therefore, it is advisable to carry the most essential medicines with you.
Quito, Bogotá and other cities are at almost 3000m above sea level. Here, altitude sickness in the form of dizziness, headache, nausea or loss of appetite might be felt. In the mountains, some of which are significantly higher, serious cases can occur, which in bad cases can lead to brain swelling or pulmonary edema.
As a precautionary measure, it is advisable to take it easy in the first few days after arrival in Quito or Bogotá and to allow enough time for acclimatization when ascending higher mountains.
Yellow fever is endemic in many regions and is transmitted by mosquitoes. The symptoms include fever, headache, abdominal pain and vomiting. A preventive vaccination is possible.
Malaria is transmitted through mosquito bites, usually at dusk. High fever, headache, body aches, chills and diarrhea are signs of possible malaria. Malaria occurs only in the lowlands below 1500m. The risk of becoming infected is considered low in the lowlands of South America.
The mosquitoes that transmit dengue fever are diurnal. The signs are similar to malaria. There is no vaccine or preventive pills.
Typhus is caused by bacteria and transmitted via contaminated drinking water or contaminated food. In the early stages of the disease, typhoid fever may feel like a bad cold. In a later stage high fever, nausea and vomiting are not uncommon. A vaccine is available.
Detailed information is available, for example, on the homepage of the tropical institute in Vienna: Tropeninstitut Wien